This project analyses a complete neuronal pathway in the locust, from sensory input to motor output. It starts at the retina, thence to the visual interneurons of the lamina and medulla (which are responsible for visual integration and coding), to Movement Detector (MD) interneurons of the lobula and brain, and finally to their postsynaptic motorneurons in the thorax. The pathway, already known in some detail, mediates escape jumping in response to certain specific classes of visual input. The behavior is of special interest because of its lability; it shows habituation, dishabituation, arousal, long-term gating, and possibly shor-term memory, as well as interaction with other sensory inputs. We hope to explain all aspects of this behavioural lability in terms of the biophysics of identified visual interneurons. The technique involves extracellular recognition of participating cells, intracellular dye-injection for anatomical visualization, intracelluar recording for analysis of synaptic and other transmissive mechanisms, and the correlation of neurophysiological function with neuro-anatomical geometry.